Basic conditions for sprinklers above suspended ceilings

Basic conditions for sprinklers above suspended ceilings

I registered today, so first of all I´d like to introduce myself. I´m working as an HVAC engineer for a german engineering office which is just starting a project in Washington DC. Please overlook the mistakes I make in orthography, my english is not that perfect.

In order to find out what we have to regard for sprinkler I need your advice. We need to understand the basic conditions for sprinklers above a suspended ceiling. We already have got the NFPA 13, but we haven´t found the answer in 8.15.1. We guess, that there is a limit of height, where there are no sprinklers required. For example in Germany, it is not necessary to install sprinkler if the height (top edge of the suspended ceiling to bottom edge of the ceiling) is less than 2,625 ft / 31,5 in / 0,8 m and there are no combustible materials.

We please you to help us out, thank you very much in advance.

RE: Basic conditions for sprinklers above suspended ceilings

8.14.1.2* Concealed Spaces Not Requiring Sprinkler Protection.8.14.1.2.1 Noncombustible and limited combustible concealed spaces with no combustible loading having no access shall not require sprinkler protection. The space shall be considered a concealed space even with small openings such as those used as return air for a plenum.

Additionally

8.14.1.2.2 Noncombustible and limited combustible concealed spaces with limited access and not permitting occupancy or storage of combustibles shall not require sprinkler protection. The space shall be considered a concealed space even with small openings such as those used as return air for a plenum.8.14.1.2.3 Concealed spaces formed by studs or joists with less than 6 in. (152 mm) between the inside or near edges of the studs or joists shall not require sprinkler protection. (See Figure 8.6.4.1.5.1.)8.14.1.2.4 Concealed spaces formed by bar joists with less than 6 in. (152 mm) between the roof or floor deck and ceiling shall not require sprinkler protection.8.14.1.2.5 Concealed spaces formed by ceilings attached directly to or within 6 in. (152 mm) of wood joist construction shall not require sprinkler protection.

RE: Basic conditions for sprinklers above suspended ceilings

1) Please help us to understand the meaning of "having no access". Does access mean also openings for maintenance?

2) In A.8.15.1.2.1 (NFPA 2007) is written:"Minor quantities of combustible materials such as but not limited to: cabeling, nonmetallic plumbing piping, nonstructural wood, etc. can be present in concealed spaces constructed of limited or noncombustible materials but should not typically be viewed as requiring sprinklers. For example, it is not intent of this section to require sprinklers, which would not otherwise be required, in the interstitial space of a typical office building solely due to the presence of the usual amount of cabeling within the space. The threshold value at which sprinklers become necessary in the concealed space is not defined".

We have in our project an typically office building with offices and a corridor in the center. The building is made out of steel and concret.In the suspended ceiling above the offices we have cabeling covered by metal pipes. But there is also opening for maintenace. In addition there will be sprinkler pipes for the sprinkler under the suspended ceiling, and pipes for the heating and cooling system (cooling with armaflex insulation).Above the corridor there will be installed ducts for the ventilation system and cable trays for the internal and external network plus telephone. The cabeling will be done starlike, so that many cables will be installed. The trays will be covered with metall.

So far we think, that it is not necessary to put sprinklers inside the suspended ceiling, because the quantities of combustible materials is present but low. What do you think?